1. Field of the Invention
The present invention relates in general to a method of disinfecting a contact lens and a disinfecting liquid used for the method, and more particularly to a technique for disinfecting the contact lens using a disinfecting liquid which is capable of exhibiting an excellent disinfecting effect.
2. Discussion of the Related Art
Conventionally, contact lenses are classified into non-water-contained or non-water-absorptive contact lenses and water-contained or water-absorptive contact lenses, or hard contact lenses and soft contact lenses. During a long period of use of the contact lenses, microorganisms such as bacteria and fungi tend to adhere to and proliferate on the surface of the contact lenses while the contact lenses are stored after they have been removed from the eyes. Such microorganisms may cause infectious diseases, giving adverse influences on the eyes of the lens user. In view of the above, the contact lenses need to be disinfected before they are worn on the eyes. In particular, it is indispensable to disinfect the soft contact lenses since the microorganisms are likely to proliferate on the surfaces of the soft contact lenses more often than on the hard contact lenses, increasing a risk of causing the infectious diseases.
A thermal disinfecting method using a suitable boiling and disinfecting device, and a chemical disinfecting method using a suitable chemical agent such as a disinfectant or a preservative have been used to disinfect contact lenses. The thermal disinfecting method inevitably requires a time-consuming boiling operation to disinfect the contact lenses. Accordingly, in recent years, the chemical disinfecting method has been widely employed to disinfect the contact lenses.
In the chemical disinfecting method, a liquid agent for contact lenses which contains a suitable disinfectant/preservative is used. The contact lenses are immersed in the liquid agent, so that the intended disinfecting treatment is conducted on the contact lenses. As the disinfectant/preservative contained in the contact lens liquid agent, JP-A-52-109953, JP-A-62-153217 and JP-A-63-59960 disclose chlorohexidine, benzalconium chloride and thimerosal, for instance.
When the contact lens is disinfected by the chemical disinfecting method, the disinfectant/preservative, such as chlorohexidine described above is generally contained in a relatively high concentration in the contact lens liquid agent, for the purpose of obtaining a sufficiently high degree of disinfecting effect. In this case, the disinfectant/preservative such as chlorohexidine is likely to be adsorbed on the contact lenses on a molecular level, deteriorating the wettability on the surface of the contact lenses and causing a change in the physical properties and configuration of the contact lenses. In some cases, the adsorption of the disinfectant/preservative on the contact lenses may cause various troubles with the eyes when the contact lenses are worn on the eyes. To keep the physical properties and configuration of the contact lenses from changing and to assure a high degree of safety to the eyes of the lens user, the contact lenses may be disinfected by using a liquid agent in which the disinfectant/preservative is contained in a relatively low concentration. In this case, however, the disinfecting effect to be exhibited by the liquid agent is inevitably lowered, causing contamination of the contact lenses by the microorganisms such as bacteria and fungi. Accordingly, when the contact lenses are disinfected by using such a conventional liquid agent, it is necessary to exercise an utmost care in adjusting the concentration of the disinfectant/preservative included in the liquid agent, making the disinfecting treatment of the contact lenses cumbersome.
As the disinfectant/preservative used in the chemical disinfecting method, hydrogen peroxide is also well known. When the hydrogen peroxide is used as the disinfectant/preservative, however, the concentration of the hydrogen peroxide needs to be generally as high as 3% (30000 ppm) to obtain an intended disinfecting effect.
The disinfectant/preservative contained in the contact lens liquid agent which is used in the chemical disinfecting method acts directly on the microorganisms such as bacteria and fungi, thereby exhibiting its disinfecting effect. Accordingly, the disinfectant/preservative is gradually decomposed and dissipated during use of the liquid agent, so that the liquid agent does not exhibit its disinfecting effect to a satisfactory extent. Thus, it is inevitably impossible to repeatedly use such a contact lens liquid agent, which may increase an economical burden on the lens user.
Metal phthalocyanine compounds are conventionally known as a catalyst having an oxidation-reduction function or ability. It is also known that a metal phthalocyanine compound exhibits a disinfecting effect with respect to harmful, pathogenic microorganisms based on its oxidation power, as disclosed in JP-A-6-321711, JP-A-63-264064, JP-A-2-139477, and JP-A-6-73397. However, it has never been known heretofore to use a metal phthalocyanine compound having a disinfecting effect for disinfecting contact lenses. Up to now, no techniques or methods have been known to effectively and safely disinfect contact lenses using a metal phthalocyanine compound.